Have scientists calculated how much oxygen is required to remain in the atmosphere to maintain the equilibrium of oxygen required to maintain an atmosphere adequate to keep humans alive ?

monkey skipper said:

Have scientists calculated how much oxygen is required to remain in the atmosphere to maintain the equilibrium of oxygen required to maintain an atmosphere adequate to keep humans alive ?

I think there is an excess of words in this question.

KJW said:

monkey skipper said:

Have scientists calculated how much oxygen is required to remain in the atmosphere to maintain the equilibrium of oxygen required to maintain an atmosphere adequate to keep humans alive ?

I think there is an excess of words in this question.

You are smart enough to work out the question. But focus on something else because that is more important

monkey skipper said:

Have scientists calculated how much oxygen is required to remain in the atmosphere to maintain the equilibrium of oxygen required to maintain an atmosphere adequate to keep humans alive ?

If you leave the words “maintain the equilibrium” out of the question then the answer is “yes”. But there are also several different oxygen levels depending on how “fit” the humans are and how long they have to acclimatise to the lower oxygen levels.

The definition of “fitness” is measured as oxygen consumption. Mount Everest (8,848 metres) was first climbed without supplemental oxygen in 1978. That’s an oxygen concentration of 21% of that at sea level. So the fittest humans can, after acclimation, survive at that oxygen concentration.

The least fit humans require more that 100% of sea level oxygen, that’s why we have oxygen tents and supplemental oxygen supply in hospitals.

Minor symptoms of altitude sickness occur at at altitude of 1,500 metres, serious altitude sickness commonly starts to occur at 2,400 metres.

On the other hand, when “equilibrium” is added to the question then the question seems to make no sense.

mollwollfumble said:

The definition of “fitness” is measured as oxygen consumption. Mount Everest (8,848 metres) was first climbed without supplemental oxygen in 1978. That’s an oxygen concentration of 21% of that at sea level. So the fittest humans can, after acclimation, survive at that oxygen concentration

Not for too long though. Even the fittest/most acclimatised human will die after a few days up that high. It’s happened a few times.

Looks like a few people other than me can’t sleep either.

To mean the balance would be when does not the earth have oxygen saturations in the atmosphere relative to the rate of population increase where by life becomes impossible ?

For example, how much oxygen is in our atmosphere now ?

Although to understand further the mixture of gases would need to be included since a pure oxygen atmosphere does not exist and would not keep us all alive either for several obvious and known reasons.

To me tipping the balance would be….when does the ever increasing population levels begin to exceed the replenishment levels of adequate oxygen gas production and other needed gases to sustain life?

The altitude answer means at what concentration levels but not when.

Would there come a time where by human populations would be impacted to the point the decline of populations would occur and only continue growth or maintain a set level relative to the levels of oxygen and other gases in our future?

Even with the current population of the World, people can acclimatise to living long term at high altitudes. TATE tells me that the highest town is at 5100 m, and there are “miners’ shacks” above that.

But if the reduction in oxygen happened sufficiently slowly evolution would allow people to adapt to survive long term at much lower oxygen levels. We don’t know the mechanisms that put limits on that, and there is no way to test them.

So the answer to the question is no.

The Rev Dodgson said:

Even with the current population of the World, people can acclimatise to living long term at high altitudes. TATE tells me that the highest town is at 5100 m, and there are “miners’ shacks” above that.

But if the reduction in oxygen happened sufficiently slowly evolution would allow people to adapt to survive long term at much lower oxygen levels. We don’t know the mechanisms that put limits on that, and there is no way to test them.

So the answer to the question is no.

So we have a yes from Molly and a no from the Rev

Apple is planning a new headquarters in the Himalayas , they have bought an old monastery

the rarefied air comcentrates the mind and helps it’s updates cleanse and purge people’s phones , after all, there is no free will – only Apple

monkey skipper said:

So we have a yes from Molly and a no from the Rev

Not unusual :)

wookiemeister said:

Apple is planning a new headquarters in the Himalayas , they have bought an old monastery

the rarefied air comcentrates the mind and helps it’s updates cleanse and purge people’s phones , after all, there is no free will – only Apple

I like that.

Maybe wookie has been spending some time in the Himalayas himself.

monkey skipper said:

Have scientists calculated how much oxygen is required to remain in the atmosphere to maintain the equilibrium of oxygen required to maintain an atmosphere adequate to keep humans alive ?

Yes

dv said:

monkey skipper said:

Have scientists calculated how much oxygen is required to remain in the atmosphere to maintain the equilibrium of oxygen required to maintain an atmosphere adequate to keep humans alive ?

Yes

Where and how?

Actually, on reflection, I have to admit I inserted an implied “meaningful” in the question. I agree that he calculation has almost certainly been done, it’s just that the answer is almost certainly wrong.

monkey skipper said:

To mean the balance would be when does not the earth have oxygen saturations in the atmosphere relative to the rate of population increase where by life becomes impossible ?

For example, how much oxygen is in our atmosphere now ?

Although to understand further the mixture of gases would need to be included since a pure oxygen atmosphere does not exist and would not keep us all alive either for several obvious and known reasons.

For “life as we know it” in general, 0% oxygen is sufficient. May microbes are strict anaerobes, can’t live in the presence of any free oxygen. The first life on Earth was anaerobic as well.

For warm blooded creatures like mammals and birds, the answer becomes an interesting one. Warm blooded animals use oxygen for internal heating as well as for energy. Hibernating animals (both warm blooded eg. bat / dormouse and cold blooded eg. weta) can survive on a much lower atmospheric oxygen content than phsyically active animals.

For humans, as stated above, it depends on how much time is needed for accimatisation. People in the villages on the Altiplano have adaptions such as stockier build and larger lungs that helps them cope with the lower oxygen content of the air.

For inert gases other than oxygen, for example nitrogen, the amount of inert gas needs to be large enough to avoid the boiling of water (or rapid evaporation) at blood temperature, unless great amounts of water for rehydration are available. 7% of atmospheric at a minimum. Compare the need for 4.4% oxygen by Everest climbers.

I’ve heard wildly different stories about breathing pure oxygen at atmospheric pressure. One is that it’s harmless and very enjoyable. The other is that it’s deadly.

There is also an upper limit on atmospheric oxygen for plant life. Too high and they catch fire too easily.

Now searching for animal altitude records.

Oops, the oxygen content at the top of Everest is 31% of that at ground level, not 21%. Please correct what I’ve said above.

mollwollfumble said:

Now searching for animal altitude records.

https://en.wikipedia.org/wiki/List_of_birds_by_flight_heights

“Rüppell’s vulture has been found at heights up to 11,300 metres”

That 21% of the oxygen content at ground level.

An unprotected human being flew a hang glider up to 9,947 metres, higher than Mt Everest. She passed out on the way up and stayed unconscious for 40 minutes or more, regaining consciousness on the way down at 6,900 metres.

mollwollfumble said:

Now searching for animal altitude records.

Well TATE is very non-specific about maximum levels:
https://en.wikipedia.org/wiki/Organisms_at_high_altitude

but the vulture flying 11 km up is quite interesting.

Does the % oxygen content vary significantly with height?

Earths oxygen is slowly leaking

The Rev Dodgson said:

Does the % oxygen content vary significantly with height?

No. The gases are well mixed. Even up to an altitude near 100 km the oxygen to nitrogen ratio stays nearly the same. Above 100 km, though, the ratio changes like this.

http://www.gi.alaska.edu/files/ioncomp.gif

Earth’s atmosphere is slowly leaking oxygen, and scientists aren’t sure why

“We are consuming O2 at a rate a factor of a thousand times faster than before,” he told Gizmodo. “Humankind has completely short-circuited the cycle by burning tonnes of carbon… it’s yet another indication of our collective ability to do what happens on the Earth, yet so much faster.”

CrazyNeutrino said:

Earth’s atmosphere is slowly leaking oxygen, and scientists aren’t sure why

I know why. Ionisation from UV light, gives ozone at lower levels but atomic oxygen at high altitudes. The ionisation of atomic oxygen at altitudes above 200km allows Earth’s magnetic field to … etc.

It’s a combination of the Jeans’ effect and sputtering. The South Atlantic Anomaly plays a role, too.

Carbon sequestration